This is another story that took place at my girlfriend's old house. At the time we were still friends, just to let you know.
One night, I was over at her house. We were sitting on her bed listening to music and talking. After a little bit of talking, I felt the bed comforter move a bit. I thought she tugged on it and didn't think anything of it. Then it was being pulled harder. We were sitting next to each other and neither of us were doing anything except sitting with our hands in plain view of each other, so I knew it wasn't her. Then the comforter was being pulled from under us to the end of the bed. I got scared and moved to the back of her bed, and so did she. I was thinking it might be her cat or something, but remembered her door was shut and there were no animals in the room.
She was so scared that she jumped into my arms and hugged me really tight. I knew she wasn't playing a trick on me and that she was really scared. The pulling of the comforter stopped and she eventually fell asleep. I was really paranoid though and I stayed sitting there for an hour just staring. It's kind of funny now that I look back and think about it, but it was real. There's nothing I can think of that can explain it except some sort of ghost.
I've heard of a story like this once and thought it was just some joke but now that I've actually experienced it, I know it's possible for stuff like this to happen.